The present invention relates to an acousto-optical spectrum analyzer.
In a prior art acousto-optical spectrum analyzer a sound wave is propagated in an interaction medium and creates in volume an index network moving at the velocity of sound V.sub.S in the material. The thus generated network diffracts an incident optical wave under Bragg conditions.
A line of detectors placed in this focal plane of a lens located at the outlet from said medium makes it possible to spectrally analyze the signal transmitted on the piezoelectric transducer which generates the sound wave in the interactive medium. However, the optical components used must be limited by diffraction in order to obtain a good resolution. This leads to the construction of spherical and cylindrical lenses with a small numerical aperture, which makes the device particularly large and difficult to regulate. In order to obviate this disadvantage, identical configurations have been proposed in integrated optics technology.
In this case, the difficulty occurs in the manufacture of wave guides with small losses and high performance geodesic lenses. Moreover, the laser-guide coupling and the guide-detector coupling constitute difficult operations leading to significant losses.